1. Field of the Invention
The invention relates to the drying and compressing of gaseous chlorine. More specifically, the invention relates to a more economical process for drying and compressing gaseous chlorine using sulfuric acid.
2. Related Art
Chlorine gas is generally commercially produced in a process wherein an electric current is passed through the typical cell, it functions to convert sodium chloride and water into three primary products: chlorine, hydrogen, and caustic soda (sodium hydroxide solution). The gas produced in the cells is both hot and wet and prior to compression and liquifaction the gas is cooled and dried. To be sold commercially, chlorine gas, as produced by the electrolysis of alkali metal chlorides (brine) in electrolytic cells, is usually compressed to the liquid form.
Various processes have been developed for drying and compressing chlorine gas which employ strong sulfuric acid as a drying agent. It is a general practice in the industry to subject the hot, wet chlorine vapor flowing from the electrolytic cells to cooling, drying and liquifaction procedures. Under these procedures, which are so commonly employed as to be considered industry standards, crude chlorine from the cells is first cooled from about 95.degree. C. to about 15.degree. C., either by direct contact of the crude chlorine vapor with water, or through surface heat exchange of the chlorine or through a combination of direct water and surface exchange. Most of the water vapor and brine spray contaminants are thereby removed. To yield a dry finished product, the cooled gaseous chlorine is then passed in countercurrent contact with concentrated sulfuric acid to accomplish removal of essentially all of the remaining water vapor and brine entrainment. Finally, the gas is compressed and condensed to yield a liquid product.
In another process, the gas is first dried and then cooled just before the gas is compressed. Employment of the above processes results in considerable expenditure for energy, and capital requirement for equipment, such as drying towers.
It is an object of the present invention to provide an improved process for drying and compressing chlorine gas. Another object of the present invention is to provide a process for drying and compressing chlorine gas having reduced cost for processing equipment and electrical energy.